In the pneumatic tires used for cars running on rough roads such as 4WD-cars and trucks, the tire sidewall portion is usually provided on the outer surface thereof with a side protector protruding therefrom in order to prevent a cut damage caused by a sharp-edged stone and the like hitting the sidewall portion when running on a rough road.
Such a side protector is conventionally formed as a rib extending continuously in the tire circumferential direction, for example, as shown in FIG. 3 of Patent Literature 1 as listed below. The ribbed part is therefore increased in the rubber volume, and the heat accumulation therein is increased. As a result, the temperature is liable to increase, which is not preferable in view of the durability.
Patent Literature 2 as listed below discloses a pneumatic tire provided in the sidewall portion with a side protector, wherein the side protector is rib-shaped, and the outer surface thereof is provided with radially extending grooves. Such grooves decrease the rubber volume of the side protector and exert a heat dissipation effect. Therefore, the heat accumulation and heat buildup can be decreased. Further, when running on a rough road, the grooves can grip the mud to improve the mud performance of the tire.
Such rib-shaped side protector with the radial grooves is, however, still not satisfactory with respect to the mud performance and the heat accumulation, and there is room for improvement.    Patent Literature 1:
Japanese Patent Application Publication No. 2003-112505    Patent Literature 2:
Japanese Patent Application Publication No. 2012-6449